Many women have not heard of implantation bleeding and instead interpret it as a sign of a light period or old blood loss. But in fact, implantation bleeding is relatively common – around 25%of pregnant women will experience some degree of bleeding in their pregnancy. Most progress to having a healthy baby nine months later.

What is implantation bleeding?

• In the earliest days of conception, the blastocyst – or ball of cells which is soon to become an embryo and eventually becomes the baby, needs to nestle down to grow. The blastocyst has already been multiplying since it left the fallopian tubes and now has to find the ideal spot in uterus to bed down for the next nine months.
• Because the uterus is so full of blood and nourishment for the blastocyst, there can be a minor disruption to the lining of the uterus and this creates light bleeding. Sometimes this is obvious and can be seen on underwear, or it may be only slight. Some women only become aware they are bleeding when they have been to the toilet and see blood on the toilet paper.
• Blood loss during an implantation bleed tends to be light, or described as “spotting”. It is mostly pinkish and watery in appearance, though it may also be a brighter red colour. After lying down for a while or first thing in the morning, the blood may be more of a brown colour. This is because it may have been sitting in the cervix or vagina for a few hours.
• It is also common to have some light uterine cramping during an implantation bleed. Not to the same degree as period pain but a vague, heavy, dull feeling in the location of the uterus. If possible, rest is recommended and beneficial. It’s also useful to avoid doing anything too strenuous. This won’t prevent the implantation bleeding from occurring, but it may help you feel you’re doing something positive by not exerting yourself.

When does implantation bleeding happen?

It normally occurs at around the same time as the period is due, around 6-12 days after ovulation and fertilisation. Which is why implantation bleeding can be both confusing and disappointing. Confusing because it can be interpreted as a light period and a sign of not being pregnant and disappointing for the same reasons. Women who are keen to conceive can become very upset at the sight of any blood loss and interpret this as a negative sign.

An implantation bleed occurs even before the pregnancy has been confirmed. Human chorionic Gonadotrophin hormone (HCG) is the hormone which is detected in the pregnant mother’s urine. This is not produced until after the embryo has embedded in the uterus and there has been some very early development of the placenta. Which is why an implantation bleed occurs too early for even the most perceptive of couples to know with any certainty that they have created a baby.

One of the symptoms of pregnancy can be having a period which is considered lighter than normal. An implantation bleed can certainly be mistaken for a period and many times it’s only with the benefit of hindsight that a woman reflects back on what she thought was an early period, but in fact, was really an implantation bleed.

What can I do to prevent implantation bleeding from happening?

Nothing really. Unless you have pain as well, or the bleeding is continuous and heavy, there really is nothing which you can do. If you have already had your pregnancy confirmed and it has been longer than two weeks since fertilisation, then an implantation bleed is unlikely.

An implantation bleed is not necessarily a bad thing. It can be a sign that fertilisation has occurred and the pregnancy is progressing as it needs to. But of course, when it happens you won’t know you’re pregnant, it’s too early to say. Some women believe that breast tenderness, nausea and other early pregnancy symptoms are also present at around the time of implantation bleeding. But this is unlikely. It is too early for the hormones which cause these symptoms to have been released by the placenta.

But the mind works in mysterious ways and some women actually “know” they are pregnant and feel very different from the moment of conception. Who is anyone else to know better?

What can I do if I have an implantation bleed?

Sit tight and don’t become anxious. Just monitor the amount that you bleed and seek the advice of your health care professional if you experience any pain or other symptoms. For the majority of women, implantation bleeding settles and stops within a day or two, not to return. It is unlikely to be to such a degree that you need to wear a pad, but for comfort’s sake many women find they prefer to use a panty liner just to be on the safe side.

If considered necessary by a health care professional, it is possible to have an ultrasound to determine if the pregnancy sac and foetus are developing as they need to. This can provide immediate reassurance that the bleeding was due to the embryo implanting, rather than indicate a miscarriage.

The foetal heart beat can be detected from around "5